[英]Spring Data JPA. Pagination for child entities
I'm using Spring Data JPA with Spring boot version 1.3.6.RELEASE with in-memory database.我将 Spring Data JPA 与 Spring Boot 版本 1.3.6.RELEASE 与内存数据库一起使用。
I'm wondering how to paginate the child entities from a parent entity.我想知道如何从父实体对子实体进行分页。 Setting fetch to LAZY is not a solution for me.
将 fetch 设置为LAZY对我来说不是解决方案。
Here is the use case :这是用例:
Here is a code sample :这是一个代码示例:
@Entity
public class Parent{
@Id
private Integer id;
@OneToMany
private List<Child> childs;
}
@Entity
public class Child {
@Id
private Integer id;
}
public interface ParentRepository extends JpaRepository<Parent, Integer>{}
public interface ChildRepository extends JpaRepository<Child, Integer>{}
I've tried this in the Parent repository unsuccessfully :我在父存储库中尝试过这个失败:
Page<Child> findById(int id, Pageable pageable);
This returns a Parent entity, not a Child entity.这将返回父实体,而不是子实体。
Any idea how to do this ?知道如何做到这一点吗?
Here is a sample of code that can fetch the child entities knowing the parent.这是一个可以获取知道父实体的子实体的代码示例。 Note that this query will return a paginated result of Child.
请注意,此查询将返回 Child 的分页结果。
/**
* Find Child entities knowing the Parent.
*/
@Query("select child from Parent p inner join p.childs child where p = :parent")
public Page<Child> findBy(@Param("parent") Parent parent, Pageable pageable);
And you can use it like this :你可以像这样使用它:
Page<Child> findBy = repo.findBy(parent, new PageRequest(page, size));
Assuming the parent is called "Parent" you can also do something like that:假设父母被称为“父母”,你也可以做这样的事情:
repo.findAllByParent(parent, pageable)
; repo.findAllByParent(parent, pageable)
;
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